Browsing by Author "Shih, Po-Jen"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
- Engineering as Technology of Technology and the Subjugated PracticeShih, Po-Jen (Virginia Tech, 2022-08-22)Two sets of concerns have motivated and sustained the research in my dissertation. First, modern ideas of technology and engineering have been over-represented by their dominant forms: that technology is all about progress and the more advanced "high" technology and that engineering chiefly concerns quantity, efficiency, problem-solving, and "better" machines. Second, these potent values in technology and engineering, as a conceptual whole, tend to reinforce each other and create conditions conducive to its sociocultural reproduction that discounts and subjugates viable alternative practices. My dissertation draws on both historical and philosophical approaches to the question of technology and engineering. My historical-linguistic study looks for the historical meanings of the two words—technology and engineering–in connection with their modern counterparts and discusses the social values and conditions that shaped the dynamics of their early development to understand and deconstruct their modern dominant representation. The analysis of ancient writings locates precedent for dominant engineering practice in ancient siege engines and military engineering, where qualities such as quantity, power, superiority, and ingenuity reinforced each other at the critical times of high-stakes siege warfare. I demonstrate how these interlocking qualities became the ideological basis for an enduring historical-conceptual structure of the dominant ideas of engineering that, despite strikingly different social contexts, continues to the present and limits the diversity of knowledge and participants. Returning back to the present, I develop a philosophical critique of contemporary engineering as "technology of technology," in that modern dominant engineering practice becomes technically provincial yet socially ambitious for our personal and institutional technical practice. In this process, certain practices in engineering, including communication, ethical reasoning, empathy, etc., have been marginalized and become what I call the "subjugated technical practice." By identifying the specific criteria and values that systematically discount and exclude the subjugated technical practice in different aspects, my analysis highlights and validates the latter's extraordinary qualities that contribute no less significantly to the success of engineering practice. Finally, to explore the possibilities of substantive policy changes, I propose theory and practice under the heading of "critical reflexive technology" and call for radical changes and critical participation from within and beyond engineering.
- On-Line Consolidation of Thermoplastic CompositesShih, Po-Jen (Virginia Tech, 1997-02-19)An on-line consolidation system, which includes a computer-controlled filament winding machine and a consolidation head assembly, has been designed and constructed to fabricate composite parts from thermoplastic towpregs. A statistical approach was used to determine the significant processing parameters and their effect on the mechanical and physical properties of composite cylinders fabricated by on-line consolidation. A central composite experimental design was used to select the processing conditions for manufacturing the composite cylinders. The thickness, density, void content, degree of crystallinity and interlaminar shear strength (ILSS) were measured for each composite cylinder. Micrographs showed that complete intimate contact and uniform fiber-matrix distribution were achieved. The degree of crystallinity of the cylinders was found to be in the range of 25-30%. Under optimum processing conditions, an ILSS of 58 MPa and a void content of <1% were achieved for APC-2 (PEEK/Carbon fiber) composite cylinders. An in-situ measurement system which uses a slip ring assembly and a computer data acquisition system was developed to obtain temperature data during winding. Composite cylinders were manufactured with eight K-type thermocouples installed in various locations inside the cylinder. The temperature distribution inside the composite cylinder during winding was measured for different processing conditions. ABAQUS finite element models of the different processes that occur during on-line consolidation were constructed. The first model was used to determine the convective heat transfer coefficient for the hot-air heat source. A convective heat transfer coefficient of 260 w/m2°K was obtained by matching the calculated temperature history to the in-situ measurement data. To predict temperature distribution during winding an ABAQUS winding simulation model was developed . The winding speed was modeled by incrementally moving the convective boundary conditions around the outer surface of the composite cylinder. A towpreg heating model was constructed to predict the temperature distribution on the cross section of the incoming towpreg. For the process-induced thermal stresses analysis, a thermoelastic finite element model was constructed. Using the temperature history obtained from thermal analysis as the initial conditions, the thermal stresses during winding and cooling were investigated.